Since most patients with pancreatic cancer present with advanced disease, pancreatic screening is needed to detect asymptomatic early-stage potentially curable lesions. In our CAncer of the Pancreas Screening (CAPS) clinical studies we have screened ~600 individuals at increased risk of developing pancreatic cancer using family history or gene mutation criteria. Screening can identify precancerous lesions and pancreatic cancers, but better circulating and pancreatic juice markers are needed to aid in pancreatic evaluation. Pancreatic juice collected from the duodenum during routine endoscopic ultrasound reveals that this sample is a rich source of biomarkers of pancreatic neoplasia and the analysis of pancreatic juice could be a useful diagnostic test. Thus, GNAS mutations are highly specific for IPMNs are specifically detected in the juice samples of patients with IPMNs. KRAS mutations are commonly found not only in the pancreatic juice of patients with pancreatic cancer, but in patients undergoing pancreatic screening even when they do not have evidence of pancreatic neoplasia by imaging. Many of these mutations are thought to arise in PanIN, which are not detected by pancreatic imaging tests because these lesions are very small and do not form masses. Thus, pancreatic juice analysis has the potential to indicate the presence of PanIN. More valuable would be a test that would indicate the grade of pancreatic neoplasia since in the absence of cancer, this is usually not possible to determine without analyzing the resected pancreas. We know that TP53 and SMAD4 mutations emerge in high-grade dysplasia and invasive pancreatic cancer tumors and can find TP53 and SMAD4 mutations in pancreatic juice samples in patients with pancreatic cancer and high-grade dysplasia, not in disease controls or those with low- grade dysplasia. To further evaluate candidate diagnostic markers we propose: Aim #1: To determine the diagnostic accuracy of mutations detected in pancreatic fluid as markers of pancreatic cancer and precancerous lesions. We will use novel nextgen sequencing methods to detect mutations in patients with pancreatic cancer, IPMNs, chronic pancreatitis, or normal pancreata. Aim #2: To evaluate circulating markers as diagnostic tests for the early detection of pancreatic cancer. We will evaluate ctDNA and exosomal markers. Aim #3: To evaluate pancreatic fluid and serum markers as tests to detect PanIN-3 and/or pre-clinical pancreatic cancer among high-risk individuals undergoing pancreatic screening and surveillance. We will develop a tissue repository of precious samples to aid in the evaluation of candidate pancreatic cancer markers, including samples from high-risk subjects and PanIN-3 lesions.